Thermosetting resin compositions are useful as a mechanical component material, an electrical or electronic component material, an automobile component material, a civil engineering and construction material, a molding material and the like. Such compositions are also used as a coating material or a material for adhesives. Inorganic substance-containing resin compositions are particularly useful as an electrical or electronic component material or a material in an optical application because such compositions can reduce a coefficient of thermal expansion and additionally control appearance of the compositions and curable products thereof and exhibit transparency if the inorganic material and the resin have equivalent refractive indexes. For example, a digital camera module has been installed on cellular phones and become smaller. Further, reduction in costs has been needed for such a module. Accordingly, plastic lens such as PMMA, PC, and polycycloolefin instead of inorganic glass have been increasingly adopted. Recently, as a new application, needs for in-vehicle applications such as an in-vehicle camera and a bar-code reader for delivery service have been increased. When used in these applications, such resin compositions need long-term heat resistance in view of exposure to summer high temperatures. Thus, thermosetting materials having more excellent heat resistance than that of conventional plastic materials have been investigated.
With respect to production methods of thermosetting resin compositions, for example, Japanese Kokai Publication No. 2004-250521 on page 2 discloses an epoxy resin molded product obtained by curing a composition containing at least an epoxy resin and inorganic oxide particles which has an average particle diameter of 50 nm or less and a redispersed into the molded product. In this application, wet silica and an epoxy resin are disclosed and bisphenol A (Abbe number of 34.1) is used as the epoxy resin. In such a case, there is room for improvement in order to improve optical characteristics such as reduction in light bleeding and increase in Abbe number. Therefore, a resin composition which has basic performances such as heat resistance and improves optical characteristics and can be preferably used as various optical members has been desired.
Further, for example, Japanese Kokai Publication No. Hei-01-272623 on pages 1 and 2 discloses that a curable resin composition include polysiloxane obtained by hydrolyzing and condensing a (tri)alkoxysilane by adding organopolysiloxane instead of the inorganic fine particles such as silica, into an epoxy resin, and thereby an internal stress of a cured product of such a curable resin composition is reduced. In addition, Japanese Kokai Publication No. Sho-58-69244 on pages 1 and 2 discloses a curable resin composition which includes, as a demolding agent, organopolysiloxane containing a specific functional group.